A comprehensive fault detection and active/reactive power output control strategy for energy storage STATCOM is proposed, which addresses the issue of transient voltage instability caused by grounding faults at the receiving-end converter station in high-voltage direct current (HVDC) transmission systems. The energy storage STATCOM possesses the capability of four-quadrant power operation, and by coordinating the active and reactive power output of the device, the voltage support effect can be optimized. First, an improved fault detection method is introduced, which utilizes dual detection to quickly determine the start and end times of faults. Second, during the fault period, the energy storage STATCOM is controlled to output a certain amount of active power, effectively suppressing continuous commutation failures at the receiving end and raising the minimum value of the AC voltage. Simultaneously, control switching of reactive power is implemented to avoid transient overvoltage issues at the receiving end caused by delayed reactive power withdrawal after fault clearance. The proposed voltage support control strategy is compared with conventional control of energy storage STATCOM using the PSCAD/EMTDC simulation platform based on the CIGRE standard system. The results indicate that the proposed control strategy achieves optimized voltage support effects in different fault scenarios.